Effects of crucible with different sizes and straight pipe on microstructure of semi-solid feedstock prepared by straight pipe pouring have been observed at different temperatures.It is found that the cooling capacity of straight pipe has some effects on microstructure of feedstock.In addition

the straight pipe has different effects on the feedstock with different size

in which the effects on microstructure of the billet with large size are higher.The desirable microstructure can be prepared by straight pipe pouring with cooling at room or water cooling for the feedstock with 80 mm in diameters and 150 mm in length

however

the microstructure is deteriorated with the pouring temperature more than 200 ℃.Although the feedstock with sound microstructure can be prepared by straight pipe pouring with cooling at room or water cooling for the billets with 98 mm in diameters and 150 mm in length

the microstructure of the semi-solid billets at water cooling is obviously superior to that of ones at room.